This invention generally relates to a dilatation catheter for angioplasty procedures such as percutaneous transluminal coronary angioplasty (PTCA).
In PTCA procedures, a dilatation catheter having an inflatable, relatively inelastic balloon on the distal end thereof is advanced through a patient's arterial system until the balloon crosses the atherosclerotic lesion to be dilated. The balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., 8 atmospheres) to dilate the stenotic region and then the balloon is deflated so that the catheter can be removed and blood flow resumed.
Usually a guiding catheter having a preformed distal end is first percutaneously introduced into the patient's arterial system and advanced therein until the distal tip of the guiding catheter is disposed in the appropriate ostium of the patient's coronary artery. A guidewire is preloaded within a dilatation catheter and both are advanced through the previously positioned guiding catheter to the distal end thereof. The guidewire is first advanced out of the guiding catheter into the patient's coronary anatomy until the distal end of the guidewire crosses the stenotic region to be dilated. The dilatation catheter is then advanced over the guidewire, with the guidewire slidably disposed within an inner lumen of the catheter until the inflatable balloon is positioned within the stenosis. The balloon is inflated to a relatively high pressure to dilate the stenosis and then deflated and removed over the guidewire. For a detailed description of procedures, reference is made to U.S. Pat. No. 4,332,254 (Lundquist), U.S. Pat. No. 4,323,071 (Simpson-Robert), U.S. Pat. No. 4,439,185 (Lundquist), U.S. Pat. No. 4,468,224 (Enzmann et al.), U.S. Pat. No. 4,516,972 (Samson), U.S. Pat. No. 4,538,622 (Samson et al.), U.S. Pat. No. 4,554,929 (Samson et al.), U.S. Pat. No. 4,569,347 (Frisbie), U.S. Pat. No. 4,571,240 (Samson et al.), U.S. Pat. No. 4,638,805 (Powell), U.S. Pat. No. 4,748,982 (Horzewski et al.), all of which are hereby incorporated herein in their entirety by reference thereto.
Efforts have been made to develop dilatation catheters which perfuse blood through an inner lumen of the catheter which traverses the interior of the balloon when the balloon is inflated during angioplasty procedures in order to avoid ischemic conditions distal to the inflated balloon. For example, dilatation catheters providing perfusion capabilities are described in U.S. Pat. No. 4,423,725 (Baran et al.) and U.S. Pat. No. 4,790,315 (Mueller, Jr. et al.) which are incorporated herein by reference thereto. See also, U.S. Pat. No. 4,581,017 (Sahota). However, these perfusion dilatation catheters generally have relatively large deflated profiles and as a result they frequently are not employed in those situations where the stenoses to be treated are deep within the patient's coronary anatomy.
Additionally, in instances where there is an acute or sudden blockage of the arterial passageway after dilatation of a stenotic region, conventional dilatation non-perfusion type catheters must first be removed from the patient before a perfusion-type dilatation catheter can be advanced over the guidewire in place within the patient. Usually, such catheter exchanges require the use of an exchange wire or extension wire such as described in U.S. Pat. No. 4,827,941 (Taylor et al.), which can add considerable time and complexity to a procedure frequently performed under emergency conditions.
What has been needed and heretofore unavailable is a perfusion-type dilatation catheter which can quickly and easily be introduced into a patient's arterial system and which has sufficient pushability to be advanced deep within the patient's vasculature. The present invention satisfies this need.